I have had several people ask me this question and I wish I could give you all the answer you are looking for. I have never played on a monitor higher than 60Hz or on anything resembling a "gaming monitor." All my experiences have been on 60Hz panels. My monitor before this was also a Dell but it was a 24" entry level one from 2009. That being said, the only fast shooter I have played on this monitor so far is Overwatch. I can sit here and say I haven't had any problems or noticed any input lag but it's subjective. Since I have nothing to compare it to, I would not really know if I am experiencing any at all. It is possible to overclock the Dell to 75Hz though. I tested mine and it worked but just for the sake of not potentially damaging it, I reverted it back to 60. I'd say If you aren't really in the market for a high refresh panel and just want an overall good experience with an ultrawide, go with this Dell. The color is fantastic.

All right, I just got 2560x1080 29UC88 like hour ago to compare with 3440x1440 34" UC98.

So far I can say:
-bleed and glow seem to be smaller on 29" model, however it is also less bright on 15% brightness than UC98 is on 0%, but I need to wait for night for accurate comparison
-size difference is enormous in favor of 34", I expected smaller difference
-difference in sharpness in games is rather negligible, lower resolution is "compensated" by smaller size on 29" model
-difference in sharpness during web browsing and etc, generally in text sharpness, is very noticeable, enough to make you fell the downgrade very clearly
-build quality is basically the same, great on both
-bezels are like 2 times bigger on 29" than on 34"
-difference in real estate is obviously enormous
-difference in colors is not too big, 29UC88 has a bit different characteristic by default by further color adjustment can make it look really close to UC98
-white is much more intense, whites on UC98 are screaming at you while on 29UC88 they are noticeably more grayish, probably coating thing
-after testing FreeSync on both 34UC98 (55-75 range) and 29UC88 (40-75 range) I am not impressed at all, the difference from standard monitor operation is noticeable but far from being worth paying extra for some gaming oriented monitor (usually Asus or Acer garbage) with better FreeSync range
-75Hz gives huge improvement over 60Hz in terms for cursor speed and smoothness on desktop, however in games the difference is not so big, but still noticeable and it is nice to have (but again, nowhere near of being a must or game changer)

All right, I just got 2560x1080 29UC88 like hour ago to compare with 3440x1440 34" UC98.

So far I can say:
-bleed and glow seem to be smaller on 29" model, however it is also less bright on 15% brightness than UC98 is on 0%, but I need to wait for night for accurate comparison
-size difference is enormous in favor of 34", I expected smaller difference
-difference in sharpness in games is rather negligible, lower resolution is "compensated" by smaller size on 29" model
-difference in sharpness during web browsing and etc, generally in text sharpness, is very noticeable, enough to make you fell the downgrade very clearly
-build quality is basically the same, great on both
-bezels are like 2 times bigger on 29" than on 34"
-difference in real estate is obviously enormous
-difference in colors is not too big, 29UC88 has a bit different characteristic by default by further color adjustment can make it look really close to UC98
-white is much more intense, whites on UC98 are screaming at you while on 29UC88 they are noticeably more grayish, probably coating thing
-after testing FreeSync on both 34UC98 (55-75 range) and 29UC88 (40-75 range) I am not impressed at all, the difference from standard monitor operation is noticeable but far from being worth paying extra for some gaming oriented monitor (usually Asus or Acer garbage) with better FreeSync range
-75Hz gives huge improvement over 60Hz in terms for cursor speed and smoothness on desktop, however in games the difference is not so big, but still noticeable and it is nice to have (but again, nowhere near of being a must or game changer)

I got my 29um68 and i absolutely LOVE freesync. I notice right away if it tears and i noticed it before on just a 60hz monitor either over or under id notice. On ps3 i can notice it right away and its super annoying. I think its amazing to have while gaming, works on dx9-dx12 and its perfect. Playing rise of the tomb raider has no tearing even down to the 40s its fantastic.

I got my 29um68 and i absolutely LOVE freesync. I notice right away if it tears and i noticed it before on just a 60hz monitor either over or under id notice. On ps3 i can notice it right away and its super annoying. I think its amazing to have while gaming, works on dx9-dx12 and its perfect. Playing rise of the tomb raider has no tearing even down to the 40s its fantastic.

Tearing never really bothered me as I basically see it only with v-sync disabled and mostly when FPS crosses refresh rate of the monitor which is not real usage thing anyway as I always use V-sync.

I hoped that FreeSync will smooth out the gameplay, reduce negative effects of FPS drops, for example clunkiness and stuttering, and this way lower my framerate target by ~10FPS so I won't have to keep this freaking 60 FPS so tightly, but it is not even close to doing this. I mean, I see the difference, but nowhere near what I could expect after reviews and opinions. I tried with 2 monitors and 2 DP cables, both certified, one supplied by LG for 34UC98, so I surely experienced proper FreeSync. Not impressive at all. It makes gaming at lower framerate a bit smoother, but you still have to to keep yourself at stable FPS at monitor's refresh rate to get proper smoothness.

Tearing never really bothered me as I basically see it only with v-sync disabled and mostly when FPS crosses refresh rate of the monitor which is not real usage thing anyway as I always use V-sync.

I hoped that FreeSync will smooth out the gameplay, reduce negative effects of FPS drops, for example clunkiness and stuttering, and this way lower my framerate target by ~10FPS so I won't have to keep this freaking 60 FPS so tightly, but it is not even close to doing this. I mean, I see the difference, but nowhere near what I could expect after reviews and opinions. I tried with 2 monitors and 2 DP cables, both certified, one supplied by LG for 34UC98, so I surely experienced proper FreeSync. Not impressive at all. It makes gaming at lower framerate a bit smoother, but you still have to to keep yourself at stable FPS at monitor's refresh rate to get proper smoothness.

Well thats also true of gsync, although it tries to double the framerate i dont think it totally works either. I dont let my fps drop below 45 anyways i find it too unsmooth.

Some games are applying their own display settings on fullscreen quite aggressively so they are losing a lot while viewed on screenshots without their default display presets, but I think they can still be shown.

First one is 38UC99, 3840x1600 38 inch monitor, 75 Hz with FreeSync at 52-75 Hz range. Price is $1500.

Second one is 34UC79G, 2560x1080 34 inch, 144 Hz with FreeSync at 50-144 Hz range, however it is unclear if this monitor is natively 2560x1080 or 3440x1440, LG site says 144 Hz at 2560x1080 but native is 3440x1440. Refresh rate at 3440x1440 is unknown. Price is $700, so this is probably not top tier panel found on 34UC88/98.Edited by Krzych04650 - 8/31/16 at 10:46am

Many mistakes there. Its 3840x1600, not 3440x1600. And 38" inch 21:9 has height similar to 30.5" 16:9 monitor, not 27", 34" ultrawide monitor has 27" 16:9 height.

This 38" panel is massive. It has height of 30.5" monitor and width of 40" monitor, or I should say TV. Probably too big for me, I am happy with 34" and I think some bigger would be problematic and tiring to use.